1. Field of the Disclosure
The present disclosure relates to a novel cleaning composition for semiconductor substrates and a method of cleaning semiconductor substrates. More particularly, the present disclosure relates to a cleaning composition for removing plasma etch residues formed on semiconductor substrates after plasma etching of metal layers or dielectric material layers deposited on the substrates and the removal of residues left on the substrate after a chemical mechanical polishing process.
2. Discussion of the Background Art
In the manufacture of integrated circuit devices, photoresists are used as an intermediate mask for transferring the original mask pattern of a reticle onto the wafer substrate by means of a series of photolithography and plasma etching steps. One of the essential steps in the integrated circuit device manufacturing process is the removal of the patterned photoresist films from the wafer substrate. In general, this step is carried out by one of two methods.
One method involves a wet stripping step in which the photoresist-covered substrate is brought into contact with a photoresist stripper solution that consists primarily of an organic solvent and an amine. However, stripper solutions cannot completely and reliably remove the photoresist films, especially if the photoresist films have been exposed to UV radiation and plasma treatments during fabrication. Some photoresist films become highly crosslinked by such treatments and are more difficult to dissolve in the stripper solution. In addition, the chemicals used in these conventional wet-stripping methods are sometimes ineffective for removing inorganic or organometallic residual materials formed during the plasma etching of metal or oxide layers with halogen-containing gases.
An alternative method of removing a photoresist film involves exposing a photoresist-coated wafer to oxygen-based plasma in order to burn the resist film from the substrate in a process known as plasma ashing. However, plasma ashing is also not fully effective in removing the plasma etching by-products noted above. Instead removal of these plasma etch by-products must be accomplished by subsequently exposing the processed metal and dielectric thin films to certain cleaning solutions.
Metal substrates are generally susceptible to corrosion. For example, substrates such as aluminum, copper, aluminum-copper alloy, tungsten nitride, and other metals and metal nitrides will readily corrode by using conventional cleaning chemistries. In addition the amount of corrosion tolerated by the integrated circuit device manufacturers is getting smaller and smaller as the device geometries shrink.
Hydroxylamine and hydroxylammonium salts are known to have excellent cleaning capabilities for residue removal on semiconductor substrates. However, recent reports have raised concerns toward the safe use of those materials and as a result there is a push by the semiconductor industry to replace hydroxylamine type components. Hence there is a need for more environmentally friendly materials.
Therefore, the cleaning solution must be effective for removing the plasma etch residues and must also be non-corrosive to all exposed substrate materials. The ability to clean the broad range of residues encountered, and be non-corrosive to exposed substrate materials is achieved by using the cleaning composition of the present disclosure. The cleaning composition of the present disclosure effectively cleans a semiconductor substrate without corroding metals contained thereon because of its weak acidic formulation, and due to the presence of combinations of water soluble organic compounds which act to enhance residue cleaning performance via oxidation and reduction mechanisms, and also whose presence performs the dual function of corrosion inhibition and trace metal chelation.